package org.opentrafficsim.road.gtu.lane;
   
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.HashMap;
   import java.util.HashSet;
   import java.util.Iterator;
   import java.util.LinkedHashMap;
   import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import javax.media.j3d.Bounds;
  import javax.vecmath.Point3d;
  
  import org.djunits.unit.DurationUnit;
  import org.djunits.unit.LengthUnit;
  import org.djunits.value.vdouble.scalar.Acceleration;
  import org.djunits.value.vdouble.scalar.Duration;
  import org.djunits.value.vdouble.scalar.Length;
  import org.djunits.value.vdouble.scalar.Speed;
  import org.djunits.value.vdouble.scalar.Time;
  import org.djutils.exceptions.Throw;
  import org.djutils.exceptions.Try;
  import org.opentrafficsim.base.parameters.ParameterException;
  import org.opentrafficsim.core.dsol.OTSSimulatorInterface;
  import org.opentrafficsim.core.geometry.OTSGeometryException;
  import org.opentrafficsim.core.geometry.OTSLine3D;
  import org.opentrafficsim.core.geometry.OTSLine3D.FractionalFallback;
  import org.opentrafficsim.core.geometry.OTSPoint3D;
  import org.opentrafficsim.core.gtu.AbstractGTU;
  import org.opentrafficsim.core.gtu.GTU;
  import org.opentrafficsim.core.gtu.GTUDirectionality;
  import org.opentrafficsim.core.gtu.GTUException;
  import org.opentrafficsim.core.gtu.GTUType;
  import org.opentrafficsim.core.gtu.RelativePosition;
  import org.opentrafficsim.core.gtu.TurnIndicatorStatus;
  import org.opentrafficsim.core.gtu.perception.EgoPerception;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlan;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlanBuilder;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlanException;
  import org.opentrafficsim.core.network.LateralDirectionality;
  import org.opentrafficsim.core.network.Link;
  import org.opentrafficsim.core.network.NetworkException;
  import org.opentrafficsim.core.perception.Historical;
  import org.opentrafficsim.core.perception.HistoricalValue;
  import org.opentrafficsim.core.perception.HistoryManager;
  import org.opentrafficsim.core.perception.collections.HistoricalLinkedHashMap;
  import org.opentrafficsim.core.perception.collections.HistoricalMap;
  import org.opentrafficsim.road.gtu.lane.perception.LanePerception;
  import org.opentrafficsim.road.gtu.lane.perception.PerceptionCollectable;
  import org.opentrafficsim.road.gtu.lane.perception.RelativeLane;
  import org.opentrafficsim.road.gtu.lane.perception.categories.DefaultSimplePerception;
  import org.opentrafficsim.road.gtu.lane.perception.categories.InfrastructurePerception;
  import org.opentrafficsim.road.gtu.lane.perception.categories.neighbors.NeighborsPerception;
  import org.opentrafficsim.road.gtu.lane.perception.headway.HeadwayGTU;
  import org.opentrafficsim.road.gtu.lane.plan.operational.LaneBasedOperationalPlan;
  import org.opentrafficsim.road.gtu.strategical.LaneBasedStrategicalPlanner;
  import org.opentrafficsim.road.network.OTSRoadNetwork;
  import org.opentrafficsim.road.network.RoadNetwork;
  import org.opentrafficsim.road.network.lane.CrossSectionElement;
  import org.opentrafficsim.road.network.lane.CrossSectionLink;
  import org.opentrafficsim.road.network.lane.DirectedLanePosition;
  import org.opentrafficsim.road.network.lane.Lane;
  import org.opentrafficsim.road.network.lane.LaneDirection;
  import org.opentrafficsim.road.network.speed.SpeedLimitInfo;
  import org.opentrafficsim.road.network.speed.SpeedLimitTypes;
  
  import nl.tudelft.simulation.dsol.SimRuntimeException;
  import nl.tudelft.simulation.dsol.formalisms.eventscheduling.SimEvent;
  import nl.tudelft.simulation.dsol.formalisms.eventscheduling.SimEventInterface;
  import nl.tudelft.simulation.dsol.logger.SimLogger;
  import nl.tudelft.simulation.dsol.simtime.SimTimeDoubleUnit;
  import nl.tudelft.simulation.language.d3.BoundingBox;
  import nl.tudelft.simulation.language.d3.DirectedPoint;
  
  /**
   * This class contains most of the code that is needed to run a lane based GTU. <br>
   * The starting point of a LaneBasedTU is that it can be in <b>multiple lanes</b> at the same time. This can be due to a lane
   * change (lateral), or due to crossing a link (front of the GTU is on another Lane than rear of the GTU). If a Lane is shorter
   * than the length of the GTU (e.g. when we do node expansion on a crossing, this is very well possible), a GTU could occupy
   * dozens of Lanes at the same time.
   * <p>
   * When calculating a headway, the GTU has to look in successive lanes. When Lanes (or underlying CrossSectionLinks) diverge,
   * the headway algorithms have to look at multiple Lanes and return the minimum headway in each of the Lanes. When the Lanes (or
   * underlying CrossSectionLinks) converge, "parallel" traffic is not taken into account in the headway calculation. Instead, gap
   * acceptance algorithms or their equivalent should guide the merging behavior.
   * <p>
   * To decide its movement, an AbstractLaneBasedGTU applies its car following algorithm and lane change algorithm to set the
   * acceleration and any lane change operation to perform. It then schedules the triggers that will add it to subsequent lanes
   * and remove it from current lanes as needed during the time step that is has committed to. Finally, it re-schedules its next
   * movement evaluation with the simulator.
   * <p>
   * Copyright (c) 2013-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision: 1408 $, $LastChangedDate: 2015-09-24 15:17:25 +0200 (Thu, 24 Sep 2015) $, by $Author: pknoppers $,
   *          initial version Oct 22, 2014 <br>
  * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
  * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
  */
 public abstract class AbstractLaneBasedGTU extends AbstractGTU implements LaneBasedGTU
 {
     /** */
     private static final long serialVersionUID = 20140822L;
 
     /** Collision detector. */
     private final CollisionDetector collisionDetector;
 
     /**
      * Fractional longitudinal positions of the reference point of the GTU on one or more links at the start of the current
      * operational plan. Because the reference point of the GTU might not be on all the links the GTU is registered on, the
      * fractional longitudinal positions can be more than one, or less than zero.
      */
     private HistoricalMap<Link, Double> fractionalLinkPositions;
 
     /**
      * The lanes the GTU is registered on. Each lane has to have its link registered in the fractionalLinkPositions as well to
      * keep consistency. Each link from the fractionalLinkPositions can have one or more Lanes on which the vehicle is
      * registered. This is a list to improve reproducibility: The 'oldest' lanes on which the vehicle is registered are at the
      * front of the list, the later ones more to the back.
      */
     private final HistoricalMap<Lane, GTUDirectionality> currentLanes;
 
     /** Pending leave triggers for each lane. */
     private Map<Lane, List<SimEventInterface<SimTimeDoubleUnit>>> pendingLeaveTriggers = new HashMap<>();
 
     /** Pending enter triggers for each lane. */
     private Map<Lane, List<SimEventInterface<SimTimeDoubleUnit>>> pendingEnterTriggers = new HashMap<>();
 
     /** Event to finalize lane change. */
     private SimEventInterface<SimTimeDoubleUnit> finalizeLaneChangeEvent = null;
 
     /** Cached desired speed. */
     private Speed cachedDesiredSpeed;
 
     /** Time desired speed was cached. */
     private Time desiredSpeedTime;
 
     /** Cached car-following acceleration. */
     private Acceleration cachedCarFollowingAcceleration;
 
     /** Time car-following acceleration was cached. */
     private Time carFollowingAccelerationTime;
 
     /** The object to lock to make the GTU thread safe. */
     private Object lock = new Object();
 
     /** The threshold distance for differences between initial locations of the GTU on different lanes. */
     @SuppressWarnings("checkstyle:visibilitymodifier")
     public static Length initialLocationThresholdDifference = new Length(1.0, LengthUnit.MILLIMETER);
 
     /** Turn indicator status. */
     private final Historical<TurnIndicatorStatus> turnIndicatorStatus;
 
     /** Caching on or off. */
     // TODO: should be indicated with a Parameter
     public static boolean CACHING = true;
 
     /** cached position count. */
     // TODO: can be removed after testing period
     public static int CACHED_POSITION = 0;
 
     /** cached position count. */
     // TODO: can be removed after testing period
     public static int NON_CACHED_POSITION = 0;
 
     /** Vehicle model. */
     private VehicleModel vehicleModel = VehicleModel.MINMAX;
 
     /**
      * Construct a Lane Based GTU.
      * @param id String; the id of the GTU
      * @param gtuType GTUType; the type of GTU, e.g. TruckType, CarType, BusType
      * @param simulator OTSSimulatorInterface; to initialize the move method and to get the current time
      * @param network OTSRoadNetwork; the network that the GTU is initially registered in
      * @throws GTUException when initial values are not correct
      */
     public AbstractLaneBasedGTU(final String id, final GTUType gtuType, final OTSSimulatorInterface simulator,
             final OTSRoadNetwork network) throws GTUException
     {
         super(id, gtuType, simulator, network);
         HistoryManager historyManager = simulator.getReplication().getHistoryManager(simulator);
         this.fractionalLinkPositions = new HistoricalLinkedHashMap<>(historyManager);
         this.currentLanes = new HistoricalLinkedHashMap<>(historyManager);
         this.turnIndicatorStatus = new HistoricalValue<>(historyManager, TurnIndicatorStatus.NOTPRESENT);
         this.collisionDetector = new CollisionDetector(id);
     }
 
     /**
      * @param strategicalPlanner LaneBasedStrategicalPlanner; the strategical planner (e.g., route determination) to use
      * @param initialLongitudinalPositions Set&lt;DirectedLanePosition&gt;; the initial positions of the car on one or more
      *            lanes with their directions
      * @param initialSpeed Speed; the initial speed of the car on the lane
      * @throws NetworkException when the GTU cannot be placed on the given lane
      * @throws SimRuntimeException when the move method cannot be scheduled
      * @throws GTUException when initial values are not correct
      * @throws OTSGeometryException when the initial path is wrong
      */
     @SuppressWarnings("checkstyle:designforextension")
     public void init(final LaneBasedStrategicalPlanner strategicalPlanner,
             final Set<DirectedLanePosition> initialLongitudinalPositions, final Speed initialSpeed)
             throws NetworkException, SimRuntimeException, GTUException, OTSGeometryException
     {
         Throw.when(null == initialLongitudinalPositions, GTUException.class, "InitialLongitudinalPositions is null");
         Throw.when(0 == initialLongitudinalPositions.size(), GTUException.class, "InitialLongitudinalPositions is empty set");
 
         DirectedPoint lastPoint = null;
         for (DirectedLanePosition pos : initialLongitudinalPositions)
         {
             // Throw.when(lastPoint != null && pos.getLocation().distance(lastPoint) > initialLocationThresholdDifference.si,
             // GTUException.class, "initial locations for GTU have distance > " + initialLocationThresholdDifference);
             lastPoint = pos.getLocation();
         }
         DirectedPoint initialLocation = lastPoint;
 
         // Give the GTU a 1 micrometer long operational plan, or a stand-still plan, so the first move and events will work
         Time now = getSimulator().getSimulatorTime();
         try
         {
             if (initialSpeed.si < OperationalPlan.DRIFTING_SPEED_SI)
             {
                 this.operationalPlan
                         .set(new OperationalPlan(this, initialLocation, now, new Duration(1E-6, DurationUnit.SECOND)));
             }
             else
             {
                 OTSPoint3D p2 = new OTSPoint3D(initialLocation.x + 1E-6 * Math.cos(initialLocation.getRotZ()),
                         initialLocation.y + 1E-6 * Math.sin(initialLocation.getRotZ()), initialLocation.z);
                 OTSLine3D path = new OTSLine3D(new OTSPoint3D(initialLocation), p2);
                 this.operationalPlan.set(OperationalPlanBuilder.buildConstantSpeedPlan(this, path, now, initialSpeed));
             }
         }
         catch (OperationalPlanException e)
         {
             throw new RuntimeException("Initial operational plan could not be created.", e);
         }
 
         // register the GTU on the lanes
         for (DirectedLanePosition directedLanePosition : initialLongitudinalPositions)
         {
             Lane lane = directedLanePosition.getLane();
             addLaneToGtu(lane, directedLanePosition.getPosition(), directedLanePosition.getGtuDirection()); // enter lane part 1
         }
 
         // init event
         DirectedLanePosition referencePosition = getReferencePosition();
         fireTimedEvent(LaneBasedGTU.LANEBASED_INIT_EVENT,
                 new Object[] {getId(), initialLocation, getLength(), getWidth(), referencePosition.getLane(),
                         referencePosition.getPosition(), referencePosition.getGtuDirection(), getGTUType()},
                 getSimulator().getSimulatorTime());
 
         // register the GTU on the lanes
         for (DirectedLanePosition directedLanePosition : initialLongitudinalPositions)
         {
             Lane lane = directedLanePosition.getLane();
             lane.addGTU(this, directedLanePosition.getPosition()); // enter lane part 2
         }
 
         // initiate the actual move
         super.init(strategicalPlanner, initialLocation, initialSpeed);
 
         this.referencePositionTime = Double.NaN; // remove cache, it may be invalid as the above init results in a lane change
 
     }
 
     /**
      * {@inheritDoc} All lanes the GTU is on will be left.
      */
     @Override
     public void setParent(final GTU gtu) throws GTUException
     {
         for (Lane lane : new HashSet<>(this.currentLanes.keySet())) // copy for concurrency problems
         {
             leaveLane(lane);
         }
         super.setParent(gtu);
     }
 
     /**
      * Reinitializes the GTU on the network using the existing strategical planner and zero speed.
      * @param initialLongitudinalPositions Set&lt;DirectedLanePosition&gt;; initial position
      * @throws NetworkException when the GTU cannot be placed on the given lane
      * @throws SimRuntimeException when the move method cannot be scheduled
      * @throws GTUException when initial values are not correct
      * @throws OTSGeometryException when the initial path is wrong
      */
     public void reinit(final Set<DirectedLanePosition> initialLongitudinalPositions)
             throws NetworkException, SimRuntimeException, GTUException, OTSGeometryException
     {
         init(getStrategicalPlanner(), initialLongitudinalPositions, Speed.ZERO);
     }
 
     /**
      * Hack method. TODO remove and solve better
      * @return safe to change
      * @throws GTUException on error
      */
     public final boolean isSafeToChange() throws GTUException
     {
         return this.fractionalLinkPositions.get(getReferencePosition().getLane().getParentLink()) > 0.0;
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public void enterLane(final Lane lane, final Length position, final GTUDirectionality gtuDirection) throws GTUException
     {
         if (lane == null || gtuDirection == null || position == null)
         {
             throw new GTUException("enterLane - one of the arguments is null");
         }
         addLaneToGtu(lane, position, gtuDirection);
         addGtuToLane(lane, position);
     }
 
     /**
      * Registers the lane at the GTU. Only works at the start of a operational plan.
      * @param lane Lane; the lane to add to the list of lanes on which the GTU is registered.
      * @param gtuDirection GTUDirectionality; the direction of the GTU on the lane (which can be bidirectional). If the GTU has
      *            a positive speed, it is moving in this direction.
      * @param position Length; the position on the lane.
      * @throws GTUException when positioning the GTU on the lane causes a problem
      */
     private void addLaneToGtu(final Lane lane, final Length position, final GTUDirectionality gtuDirection) throws GTUException
     {
         if (this.currentLanes.containsKey(lane))
         {
             System.err.println(this + " is already registered on lane: " + lane + " at fractional position "
                     + this.fractionalPosition(lane, RelativePosition.REFERENCE_POSITION) + " intended position is " + position
                     + " length of lane is " + lane.getLength());
             return;
         }
         // if the GTU is already registered on a lane of the same link, do not change its fractional position, as
         // this might lead to a "jump".
         if (!this.fractionalLinkPositions.containsKey(lane.getParentLink()))
         {
             this.fractionalLinkPositions.put(lane.getParentLink(), lane.fraction(position));
         }
         this.currentLanes.put(lane, gtuDirection);
     }
 
     /**
      * Part of 'enterLane' which registers the GTU with the lane so the lane can report its GTUs.
      * @param lane Lane; lane
      * @param position Length; position
      * @throws GTUException on exception
      */
     protected void addGtuToLane(final Lane lane, final Length position) throws GTUException
     {
         List<SimEventInterface<SimTimeDoubleUnit>> pending = this.pendingEnterTriggers.get(lane);
         if (null != pending)
         {
             for (SimEventInterface<SimTimeDoubleUnit> event : pending)
             {
                 if (event.getAbsoluteExecutionTime().get().ge(getSimulator().getSimulatorTime()))
                 {
                     boolean result = getSimulator().cancelEvent(event);
                     if (!result && event.getAbsoluteExecutionTime().get().ne(getSimulator().getSimulatorTime()))
                     {
                         System.err.println("addLaneToGtu, trying to remove event: NOTHING REMOVED -- result=" + result
                                 + ", simTime=" + getSimulator().getSimulatorTime() + ", eventTime="
                                 + event.getAbsoluteExecutionTime().get());
                     }
                 }
             }
             this.pendingEnterTriggers.remove(lane);
         }
         lane.addGTU(this, position);
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public void leaveLane(final Lane lane) throws GTUException
     {
         leaveLane(lane, false);
     }
 
     /**
      * Leave a lane but do not complain about having no lanes left when beingDestroyed is true.
      * @param lane Lane; the lane to leave
      * @param beingDestroyed boolean; if true, no complaints about having no lanes left
      * @throws GTUException in case leaveLane should not be called
      */
     @SuppressWarnings("checkstyle:designforextension")
     public void leaveLane(final Lane lane, final boolean beingDestroyed) throws GTUException
     {
         Length position = position(lane, getReference());
         this.currentLanes.remove(lane);
         removePendingEvents(lane, this.pendingLeaveTriggers);
         removePendingEvents(lane, this.pendingEnterTriggers);
         // check if there are any lanes for this link left. If not, remove the link.
         boolean found = false;
         for (Lane l : this.currentLanes.keySet())
         {
             if (l.getParentLink().equals(lane.getParentLink()))
             {
                 found = true;
             }
         }
         if (!found)
         {
             this.fractionalLinkPositions.remove(lane.getParentLink());
         }
         lane.removeGTU(this, !found, position);
         if (this.currentLanes.size() == 0 && !beingDestroyed)
         {
             System.err.println("leaveLane: lanes.size() = 0 for GTU " + getId());
         }
     }
 
     /**
      * Removes and cancels events for the given lane.
      * @param lane Lane; lane
      * @param triggers Map&lt;Lane, List&lt;SimEventInterface&lt;SimTimeDoubleUnit&gt;&gt;&gt;; map to use
      */
     private void removePendingEvents(final Lane lane, final Map<Lane, List<SimEventInterface<SimTimeDoubleUnit>>> triggers)
     {
         List<SimEventInterface<SimTimeDoubleUnit>> pending = triggers.get(lane);
         if (null != pending)
         {
             for (SimEventInterface<SimTimeDoubleUnit> event : pending)
             {
                 if (event.getAbsoluteExecutionTime().get().ge(getSimulator().getSimulatorTime()))
                 {
                     boolean result = getSimulator().cancelEvent(event);
                     if (!result && event.getAbsoluteExecutionTime().get().ne(getSimulator().getSimulatorTime()))
                     {
                         System.err.println("leaveLane, trying to remove event: NOTHING REMOVED -- result=" + result
                                 + ", simTime=" + getSimulator().getSimulatorTime() + ", eventTime="
                                 + event.getAbsoluteExecutionTime().get());
                     }
                 }
             }
             triggers.remove(lane);
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public void changeLaneInstantaneously(final LateralDirectionality laneChangeDirection) throws GTUException
     {
 
         // from info
         DirectedLanePosition from = getReferencePosition();
 
         // keep a copy of the lanes and directions (!)
         Set<Lane> lanesToBeRemoved = new LinkedHashSet<>(this.currentLanes.keySet());
 
         // store the new positions
         // start with current link position, these will be overwritten, except if from a lane no adjacent lane is found, i.e.
         // changing over a continuous line when probably the reference point is past the line
         Map<Link, Double> newLinkPositionsLC = new LinkedHashMap<>(this.fractionalLinkPositions);
 
         // obtain position on lane adjacent to reference lane and enter lanes upstream/downstream from there
         Set<Lane> adjLanes = from.getLane().accessibleAdjacentLanesPhysical(laneChangeDirection, getGTUType(),
                 this.currentLanes.get(from.getLane()));
         Lane adjLane = adjLanes.iterator().next();
         Length position = adjLane.position(from.getLane().fraction(from.getPosition()));
         GTUDirectionality direction = getDirection(from.getLane());
         Length planLength = Try.assign(() -> getOperationalPlan().getTraveledDistance(getSimulator().getSimulatorTime()),
                 "Exception while determining plan length.");
         enterLaneRecursive(new LaneDirection(adjLane, direction), position, newLinkPositionsLC, planLength, lanesToBeRemoved,
                 0);
 
         // update the positions on the lanes we are registered on
         this.fractionalLinkPositions.clear();
         this.fractionalLinkPositions.putAll(newLinkPositionsLC);
 
         // leave the from lanes
         for (Lane lane : lanesToBeRemoved)
         {
             leaveLane(lane);
         }
 
         // stored positions no longer valid
         this.referencePositionTime = Double.NaN;
         this.cachedPositions.clear();
 
         // fire event
         this.fireTimedEvent(LaneBasedGTU.LANE_CHANGE_EVENT, new Object[] {getId(), laneChangeDirection, from},
                 getSimulator().getSimulatorTime());
 
     }
 
     /**
      * Enters lanes upstream and downstream of the new location after an instantaneous lane change.
      * @param lane LaneDirection; considered lane
      * @param position Length; position to add GTU at
      * @param newLinkPositionsLC Map&lt;Link, Double&gt;; new link fractions to store
      * @param planLength Length; length of plan, to consider fractions at start
      * @param lanesToBeRemoved Set&lt;Lane&gt;; lanes to leave, from which lanes are removed when entered (such that they arent
      *            then left)
      * @param dir int; below 0 for upstream, above 0 for downstream, 0 for both
      * @throws GTUException on exception
      */
     private void enterLaneRecursive(final LaneDirection lane, final Length position, final Map<Link, Double> newLinkPositionsLC,
             final Length planLength, final Set<Lane> lanesToBeRemoved, final int dir) throws GTUException
     {
         enterLane(lane.getLane(), position, lane.getDirection());
         lanesToBeRemoved.remove(lane);
         Length adjusted = lane.getDirection().isPlus() ? position.minus(planLength) : position.plus(planLength);
         newLinkPositionsLC.put(lane.getLane().getParentLink(), adjusted.si / lane.getLength().si);
 
         // upstream
         if (dir < 1)
         {
             Length rear = lane.getDirection().isPlus() ? position.plus(getRear().getDx()) : position.minus(getRear().getDx());
             Length before = null;
             if (lane.getDirection().isPlus() && rear.si < 0.0)
             {
                 before = rear.neg();
             }
             else if (lane.getDirection().isMinus() && rear.si > lane.getLength().si)
             {
                 before = rear.minus(lane.getLength());
             }
             if (before != null)
             {
                 GTUDirectionality upDir = lane.getDirection();
                 Map<Lane, GTUDirectionality> upstream = lane.getLane().upstreamLanes(upDir, getGTUType());
                 if (!upstream.isEmpty())
                 {
                     Lane upLane = null;
                     for (Lane nextUp : upstream.keySet())
                     {
                         if (newLinkPositionsLC.containsKey(nextUp.getParentLink()))
                         {
                             // multiple upstream lanes could belong to the same link, we pick an arbitrary lane
                             // (a conflict should solve this)
                             upLane = nextUp;
                             break;
                         }
                     }
                     if (upLane == null)
                     {
                         // the rear is on an upstream section we weren't before the lane change, due to curvature, we pick an
                         // arbitrary
                         // lane (a conflict should solve this)
                         upLane = upstream.keySet().iterator().next();
                     }
                     upDir = upstream.get(upLane);
                     LaneDirection next = new LaneDirection(upLane, upDir);
                     Length nextPos = upDir.isPlus() ? next.getLength().minus(before).minus(getRear().getDx())
                             : before.plus(getRear().getDx());
                     enterLaneRecursive(next, nextPos, newLinkPositionsLC, planLength, lanesToBeRemoved, -1);
                 }
             }
         }
 
         // downstream
         if (dir > -1)
         {
             Length front =
                     lane.getDirection().isPlus() ? position.plus(getFront().getDx()) : position.minus(getFront().getDx());
             Length passed = null;
             if (lane.getDirection().isPlus() && front.si > lane.getLength().si)
             {
                 passed = front.minus(lane.getLength());
             }
             else if (lane.getDirection().isMinus() && front.si < 0.0)
             {
                 passed = front.neg();
             }
             if (passed != null)
             {
                 LaneDirection next = lane.getNextLaneDirection(this);
                 Length nextPos = next.getDirection().isPlus() ? passed.minus(getFront().getDx())
                         : next.getLength().minus(passed).plus(getFront().getDx());
                 enterLaneRecursive(next, nextPos, newLinkPositionsLC, planLength, lanesToBeRemoved, 1);
             }
         }
     }
 
     /**
      * Register on lanes in target lane.
      * @param laneChangeDirection LateralDirectionality; direction of lane change
      * @throws GTUException exception
      */
     @SuppressWarnings("checkstyle:designforextension")
     public void initLaneChange(final LateralDirectionality laneChangeDirection) throws GTUException
     {
         Map<Lane, GTUDirectionality> lanesCopy = new LinkedHashMap<>(this.currentLanes);
         Map<Lane, Double> fractionalLanePositions = new HashMap<>();
         for (Lane lane : lanesCopy.keySet())
         {
             fractionalLanePositions.put(lane, fractionalPosition(lane, getReference()));
         }
         int numRegistered = 0;
         for (Lane lane : lanesCopy.keySet())
         {
             Set<Lane> laneSet = lane.accessibleAdjacentLanesLegal(laneChangeDirection, getGTUType(), getDirection(lane));
             if (laneSet.size() > 0)
             {
                 numRegistered++;
                 Lane adjacentLane = laneSet.iterator().next();
                 enterLane(adjacentLane, adjacentLane.getLength().multiplyBy(fractionalLanePositions.get(lane)),
                         lanesCopy.get(lane));
             }
         }
         Throw.when(numRegistered == 0, GTUException.class, "Gtu %s starting %s lane change, but no adjacent lane found.",
                 getId(), laneChangeDirection);
     }
 
     /**
      * Performs the finalization of a lane change by leaving the from lanes.
      * @param laneChangeDirection LateralDirectionality; direction of lane change
      */
     @SuppressWarnings("checkstyle:designforextension")
     protected void finalizeLaneChange(final LateralDirectionality laneChangeDirection)
     {
         Map<Lane, GTUDirectionality> lanesCopy = new LinkedHashMap<>(this.currentLanes);
         Set<Lane> lanesToBeRemoved = new LinkedHashSet<>();
         Lane fromLane = null;
         Length fromPosition = null;
         GTUDirectionality fromDirection = null;
         try
         {
             // find lanes to leave as they have an adjacent lane the GTU is also on in the lane change direction
             for (Lane lane : lanesCopy.keySet())
             {
                 Iterator<Lane> iterator =
                         lane.accessibleAdjacentLanesPhysical(laneChangeDirection, getGTUType(), getDirection(lane)).iterator();
                 if (iterator.hasNext() && lanesCopy.keySet().contains(iterator.next()))
                 {
                     lanesToBeRemoved.add(lane);
                 }
             }
             // some lanes registered to the GTU may be downstream of a split and have no adjacent lane, find longitudinally
             boolean added = true;
             while (added)
             {
                 added = false;
                 Set<Lane> lanesToAlsoBeRemoved = new LinkedHashSet<>();
                 for (Lane lane : lanesToBeRemoved)
                 {
                     GTUDirectionality direction = getDirection(lane);
                     for (Lane nextLane : direction.isPlus() ? lane.nextLanes(getGTUType()).keySet()
                             : lane.prevLanes(getGTUType()).keySet())
                     {
                         if (lanesCopy.containsKey(nextLane) && !lanesToBeRemoved.contains(nextLane))
                         {
                             added = true;
                             lanesToAlsoBeRemoved.add(nextLane);
                         }
                     }
                 }
                 lanesToBeRemoved.addAll(lanesToAlsoBeRemoved);
             }
             double nearest = Double.POSITIVE_INFINITY;
             for (Lane lane : lanesToBeRemoved)
             {
                 Length pos = position(lane, RelativePosition.REFERENCE_POSITION);
                 if (0.0 <= pos.si && pos.si <= lane.getLength().si)
                 {
                     fromLane = lane;
                     fromPosition = pos;
                     fromDirection = getDirection(lane);
                 }
                 else if (fromLane == null && (getDirection(lane).isPlus() ? pos.si > lane.getLength().si : pos.le0()))
                 {
                     // if the reference point is in between two lanes, this recognizes the lane upstream of the gap
                     double distance = getDirection(lane).isPlus() ? pos.si - lane.getLength().si : -pos.si;
                     if (distance < nearest)
                     {
                         nearest = distance;
                         fromLane = lane;
                         fromPosition = pos;
                         fromDirection = getDirection(lane);
                     }
                 }
                 leaveLane(lane);
             }
             this.referencePositionTime = Double.NaN;
             this.finalizeLaneChangeEvent = null;
         }
         catch (GTUException exception)
         {
             // should not happen, lane was obtained from GTU
             throw new RuntimeException("position on lane not possible", exception);
         }
         Throw.when(fromLane == null, RuntimeException.class, "No from lane for lane change event.");
         DirectedLanePosition from;
         try
         {
             from = new DirectedLanePosition(fromLane, fromPosition, fromDirection);
         }
         catch (GTUException exception)
         {
             throw new RuntimeException(exception);
         }
         this.fireTimedEvent(LaneBasedGTU.LANE_CHANGE_EVENT, new Object[] {getId(), laneChangeDirection, from},
                 getSimulator().getSimulatorTime());
     }
 
     /** {@inheritDoc} */
     @Override
     public void setFinalizeLaneChangeEvent(final SimEventInterface<SimTimeDoubleUnit> event)
     {
         this.finalizeLaneChangeEvent = event;
     }
 
     /** {@inheritDoc} */
     @Override
     public final GTUDirectionality getDirection(final Lane lane) throws GTUException
     {
         Throw.when(!this.currentLanes.containsKey(lane), GTUException.class, "getDirection: Lanes %s does not contain %s",
                 this.currentLanes.keySet(), lane);
         return this.currentLanes.get(lane);
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     protected void move(final DirectedPoint fromLocation)
             throws SimRuntimeException, GTUException, OperationalPlanException, NetworkException, ParameterException
     {
         // DirectedPoint currentPoint = getLocation(); // used for "jump" detection that is also commented out
         // Only carry out move() if we still have lane(s) to drive on.
         // Note: a (Sink) trigger can have 'destroyed' us between the previous evaluation step and this one.
         if (this.currentLanes.isEmpty())
         {
             destroy();
             return; // Done; do not re-schedule execution of this move method.
         }
 
         // remove enter events
         // WS: why?
         // for (Lane lane : this.pendingEnterTriggers.keySet())
         // {
         // System.out.println("GTU " + getId() + " is canceling event on lane " + lane.getFullId());
         // List<SimEventInterface<SimTimeDoubleUnit>> events = this.pendingEnterTriggers.get(lane);
         // for (SimEventInterface<SimTimeDoubleUnit> event : events)
         // {
         // // also unregister from lane
         // this.currentLanes.remove(lane);
         // getSimulator().cancelEvent(event);
         // }
         // }
         // this.pendingEnterTriggers.clear();
 
         // get distance covered in previous plan, to aid a shift in link fraction (from which a plan moves onwards)
         Length covered;
         if (getOperationalPlan() instanceof LaneBasedOperationalPlan
                 && ((LaneBasedOperationalPlan) getOperationalPlan()).isDeviative())
         {
             // traveled distance as difference between start and current position on reference lane
             // note that for a deviative plan the traveled distance along the path is not valuable here
             LaneBasedOperationalPlan plan = (LaneBasedOperationalPlan) getOperationalPlan();
             DirectedLanePosition ref = getReferencePosition();
             covered = ref.getGtuDirection().isPlus()
                     ? position(ref.getLane(), getReference())
                             .minus(position(ref.getLane(), getReference(), plan.getStartTime()))
                     : position(ref.getLane(), getReference(), plan.getStartTime())
                             .minus(position(ref.getLane(), getReference()));
             // Note that distance is valid as the reference lane can not change (and location of previous plan is start location
             // of current plan). Only instantaneous lane changes can do that, which do not result in deviative plans.
         }
         else
         {
             covered = getOperationalPlan().getTraveledDistance(getSimulator().getSimulatorTime());
         }
 
         // generate the next operational plan and carry it out
         // in case of an instantaneous lane change, fractionalLinkPositions will be accordingly adjusted to the new lane
         super.move(fromLocation);
 
         // update the positions on the lanes we are registered on
         // WS: this was previously done using fractions calculated before super.move() based on the GTU position, but an
         // instantaneous lane change while e.g. the nose is on the next lane which is curved, results in a different fraction on
         // the next link (the GTU doesn't stretch or shrink)
         Map<Link, Double> newLinkFractions = new LinkedHashMap<>(this.fractionalLinkPositions);
         Set<Link> done = new LinkedHashSet<>();
         // WS: this used to be on all current lanes, skipping links already processed, but 'covered' regards the reference lane
         updateLinkFraction(getReferencePosition().getLane(), newLinkFractions, done, false, covered, true);
         updateLinkFraction(getReferencePosition().getLane(), newLinkFractions, done, true, covered, true);
         this.fractionalLinkPositions.clear();
         this.fractionalLinkPositions.putAll(newLinkFractions);
 
         DirectedLanePosition dlp = getReferencePosition();
         fireTimedEvent(
                 LaneBasedGTU.LANEBASED_MOVE_EVENT, new Object[] {getId(), fromLocation, getSpeed(), getAcceleration(),
                         getTurnIndicatorStatus(), getOdometer(), dlp.getLane(), dlp.getPosition(), dlp.getGtuDirection()},
                 getSimulator().getSimulatorTime());
 
         if (getOperationalPlan().getAcceleration(Duration.ZERO).si < -10
                 && getOperationalPlan().getSpeed(Duration.ZERO).si > 2.5)
         {
             System.err.println("GTU: " + getId() + " - getOperationalPlan().getAcceleration(Duration.ZERO).si < -10)");
             System.err.println("Lanes in current plan: " + this.currentLanes.keySet());
             if (getTacticalPlanner().getPerception().contains(DefaultSimplePerception.class))
             {
                 DefaultSimplePerception p =
                         getTacticalPlanner().getPerception().getPerceptionCategory(DefaultSimplePerception.class);
                 System.err.println("HeadwayGTU: " + p.getForwardHeadwayGTU());
                 System.err.println("HeadwayObject: " + p.getForwardHeadwayObject());
             }
         }
         // DirectedPoint currentPointAfterMove = getLocation();
         // if (currentPoint.distance(currentPointAfterMove) > 0.1)
         // {
         // System.err.println(this.getId() + " jumped");
         // }
         // schedule triggers and determine when to enter lanes with front and leave lanes with rear
         scheduleEnterLeaveTriggers();
     }
 
     /**
      * Recursive update of link fractions based on a moved distance.
      * @param lane Lane; current lane, start with reference lane
      * @param newLinkFractions Map&lt;Link, Double&gt;; map to put new fractions in
      * @param done Set&lt;Link&gt;; links to skip as link are already done
      * @param prevs boolean; whether to loop to the previous or next lanes, regardless of driving direction
      * @param covered Length; covered distance along the reference lane
      * @param isReferenceLane boolean; whether this lane is the reference lane (to skip in second call)
      */
     private void updateLinkFraction(final Lane lane, final Map<Link, Double> newLinkFractions, final Set<Link> done,
             final boolean prevs, final Length covered, final boolean isReferenceLane)
     {
         if (!prevs || !isReferenceLane)
         {
             if (done.contains(lane.getParentLink()) || !this.currentLanes.containsKey(lane))
             {
                 return;
             }
             double sign;
             try
             {
                 sign = getDirection(lane).isPlus() ? 1.0 : -1.0;
             }
             catch (GTUException exception)
             {
                 // can not happen as we check that the lane is in the currentLanes
                 throw new RuntimeException("Unexpected exception: trying to obtain direction on lane.", exception);
             }
             newLinkFractions.put(lane.getParentLink(),
                     this.fractionalLinkPositions.get(lane.getParentLink()) + sign * covered.si / lane.getLength().si);
             done.add(lane.getParentLink());
         }
         for (Lane nextLane : (prevs ? lane.prevLanes(getGTUType()) : lane.nextLanes(getGTUType())).keySet())
         {
             updateLinkFraction(nextLane, newLinkFractions, done, prevs, covered, false);
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public final Map<Lane, Length> positions(final RelativePosition relativePosition) throws GTUException
     {
         return positions(relativePosition, getSimulator().getSimulatorTime());
     }
 
     /** {@inheritDoc} */
     @Override
     public final Map<Lane, Length> positions(final RelativePosition relativePosition, final Time when) throws GTUException
     {
         Map<Lane, Length> positions = new LinkedHashMap<>();
         for (Lane lane : this.currentLanes.keySet())
         {
             positions.put(lane, position(lane, relativePosition, when));
         }
         return positions;
     }
 
     /** {@inheritDoc} */
     @Override
     public final Length position(final Lane lane, final RelativePosition relativePosition) throws GTUException
     {
         return position(lane, relativePosition, getSimulator().getSimulatorTime());
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public Length translatedPosition(final Lane projectionLane, final RelativePosition relativePosition, final Time when)
             throws GTUException
     {
         CrossSectionLink link = projectionLane.getParentLink();
         for (CrossSectionElement cse : link.getCrossSectionElementList())
         {
             if (cse instanceof Lane)
             {
                 Lane cseLane = (Lane) cse;
                 if (null != this.currentLanes.get(cseLane))
                 {
                     double fractionalPosition = fractionalPosition(cseLane, RelativePosition.REFERENCE_POSITION, when);
                     Length pos = new Length(projectionLane.getLength().getSI() * fractionalPosition, LengthUnit.SI);
                     if (this.currentLanes.get(cseLane).isPlus())
                     {
                         return pos.plus(relativePosition.getDx());
                     }
                     return pos.minus(relativePosition.getDx());
                 }
             }
         }
         throw new GTUException(this + " is not on any lane of Link " + link);
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public Length projectedPosition(final Lane projectionLane, final RelativePosition relativePosition, final Time when)
             throws GTUException
     {
         CrossSectionLink link = projectionLane.getParentLink();
         for (CrossSectionElement cse : link.getCrossSectionElementList())
         {
             if (cse instanceof Lane)
             {
                 Lane cseLane = (Lane) cse;
                 if (null != this.currentLanes.get(cseLane))
                 {
                     double fractionalPosition = fractionalPosition(cseLane, relativePosition, when);
                     return new Length(projectionLane.getLength().getSI() * fractionalPosition, LengthUnit.SI);
                 }
             }
         }
         throw new GTUException(this + " is not on any lane of Link " + link);
     }
 
     /** caching of time field for last stored position(s). */
     private double cachePositionsTime = Double.NaN;
 
     /** caching of last stored position(s). */
     private Map<Integer, Length> cachedPositions = new HashMap<>();
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public Length position(final Lane lane, final RelativePosition relativePosition, final Time when) throws GTUException
     {
         int cacheIndex = 0;
         if (CACHING)
         {
             cacheIndex = 17 * lane.hashCode() + relativePosition.hashCode();
             Length l;
             if (when.si == this.cachePositionsTime && (l = this.cachedPositions.get(cacheIndex)) != null)
             {
                 // PK verify the result; uncomment if you don't trust the cache
                 // this.cachedPositions.clear();
                 // Length difficultWay = position(lane, relativePosition, when);
                 // if (Math.abs(l.si - difficultWay.si) > 0.00001)
                 // {
                 // System.err.println("Whoops: cache returns bad value for GTU " + getId());
                 // }
                 CACHED_POSITION++;
                 return l;
             }
             if (when.si != this.cachePositionsTime)
             {
                 this.cachedPositions.clear();
                 this.cachePositionsTime = when.si;
             }
         }
         NON_CACHED_POSITION++;
 
         synchronized (this.lock)
         {
             double longitudinalPosition;
             try
             {
                 longitudinalPosition = lane.positionSI(this.fractionalLinkPositions.get(when).get(lane.getParentLink()));
             }
             catch (NullPointerException exception)
             {
                 throw exception;
             }
             double loc = Double.NaN;
             try
             {
                 OperationalPlan plan = getOperationalPlan(when);
                 if (!(plan instanceof LaneBasedOperationalPlan) || !((LaneBasedOperationalPlan) plan).isDeviative())
                 {
                     if (this.currentLanes.get(when).get(lane).isPlus())
                     {
                         loc = longitudinalPosition + plan.getTraveledDistanceSI(when) + relativePosition.getDx().si;
                     }
                     else
                     {
                         loc = longitudinalPosition - plan.getTraveledDistanceSI(when) - relativePosition.getDx().si;
                     }
                 }
                 else
                 {
                     // deviative LaneBasedOperationalPlan, i.e. the GTU is not on a center line
                     DirectedPoint p = plan.getLocation(when, relativePosition);
                     double f = lane.getCenterLine().projectFractional(null, null, p.x, p.y, FractionalFallback.NaN);
                     if (!Double.isNaN(f))
                     {
                         loc = f * lane.getLength().si;
                     }
                     else
                     {
                         // the point does not project fractionally to this lane, it has to be up- or downstream of the lane
 
                         // simple heuristic to decide if we first look upstream or downstream
                         boolean upstream = this.fractionalLinkPositions.get(lane.getParentLink()) < 0.0 ? true : false;
 
                         // use loop up to 2 times (for loop creates 'loc not initialized' warning)
                         int i = 0;
                         while (true)
                         {
                             Set<Lane> otherLanesToConsider = new LinkedHashSet<>();
                             otherLanesToConsider.addAll(this.currentLanes.keySet());
                             double distance = getDistanceAtOtherLane(lane, when, upstream, 0.0, p, otherLanesToConsider);
                             // distance can be positive on an upstream lane due to a loop
                             if (!Double.isNaN(distance))
                             {
                                 if (i == 1 && !Double.isNaN(loc))
                                 {
                                     // loc was determined in both loops, this constitutes a lane-loop, select nearest
                                     double loc2 = upstream ? -distance : distance + lane.getLength().si;
                                     double d1 = loc < 0.0 ? -loc : loc - lane.getLength().si;
                                     double d2 = loc2 < 0.0 ? -loc2 : loc2 - lane.getLength().si;
                                     loc = d1 < d2 ? loc : loc2;
                                     break;
                                 }
                                 else
                                 {
                                     // loc was determined in second loop
                                     loc = upstream ? -distance : distance + lane.getLength().si;
                                 }
                             }
                             else if (!Double.isNaN(loc))
                             {
                                 // loc was determined in first loop
                                 break;
                             }
                             else if (i == 1)
                             {
                                 // loc was determined in neither loop
                                 // Lane change ended while moving to next link. The source lanes are left and for a leave-lane
                                 // event the position is required. This may depend on upstream or downstream lanes as the
                                 // reference position is projected to that lane. But if we already left that lane, we can't use
                                 // it. We thus use ENDPOINT fallback instead.
                                 loc = lane.getLength().si * lane.getCenterLine().projectFractional(null, null, p.x, p.y,
                                         FractionalFallback.ENDPOINT);
                                 break;
                             }
                             // try other direction
                             i++;
                             upstream = !upstream;
                         }
                     }
                 }
             }
             catch (NullPointerException e)
             {
                 throw new GTUException("lanesCurrentOperationalPlan or fractionalLinkPositions is null", e);
             }
             catch (Exception e)
             {
                 System.err.println(toString());
                 System.err.println(this.currentLanes.get(when));
                 System.err.println(this.fractionalLinkPositions.get(when));
                 throw new GTUException(e);
             }
             if (Double.isNaN(loc))
             {
                 System.out.println("loc is NaN");
             }
             Length length = Length.createSI(loc);
             if (CACHING)
             {
                 this.cachedPositions.put(cacheIndex, length);
             }
             return length;
         }
     }
 
     /** Set of lane to attempt when determining the location with a deviative lane change. */
     // private Set<Lane> otherLanesToConsider;
 
     /**
      * In case of a deviative operational plan (not on the center lines), positions are projected fractionally to the center
      * lines. For points upstream or downstream of a lane, fractional projection is not valid. In such cases we need to project
      * the position to an upstream or downstream lane instead, and adjust length along the center lines.
      * @param lane Lane; lane to determine the position on
      * @param when Time; time
      * @param upstream boolean; whether to check upstream (or downstream)
      * @param distance double; cumulative distance in recursive search, starts at 0.0
      * @param point DirectedPoint; absolute point of GTU to be projected to center line
      * @param otherLanesToConsider Set&lt;Lane&gt;; lanes to consider
      * @return Length; position on lane being &lt;0 or &gt;{@code lane.getLength()}
      * @throws GTUException if GTU is not on the lane
      */
     private double getDistanceAtOtherLane(final Lane lane, final Time when, final boolean upstream, final double distance,
             final DirectedPoint point, final Set<Lane> otherLanesToConsider) throws GTUException
     {
         Set<Lane> nextLanes = new HashSet<>(upstream == getDirection(lane).isPlus() ? lane.prevLanes(getGTUType()).keySet()
                 : lane.nextLanes(getGTUType()).keySet()); // safe copy
         nextLanes.retainAll(otherLanesToConsider); // as we delete here
         if (!upstream && nextLanes.size() > 1)
         {
             LaneDirection laneDir = new LaneDirection(lane, getDirection(lane)).getNextLaneDirection(this);
             if (nextLanes.contains(laneDir.getLane()))
             {
                 nextLanes.clear();
                 nextLanes.add(laneDir.getLane());
             }
             else
             {
                 SimLogger.always().error("Distance on downstream lane could not be determined.");
             }
         }
         // TODO When requesting the position at the end of the plan, which will be on a further lane, this lane is not yet
         // part of the lanes in the current operational plan. This can be upstream or downstream depending on the direction of
         // travel. We might check whether getDirection(lane)=DIR_PLUS and upstream=false, or getDirection(lane)=DIR_MINUS and
         // upstream=true, to then use LaneDirection.getNextLaneDirection(this) to obtain the next lane. This is only required if
         // nextLanes originally had more than 1 lane, otherwise we can simply use that one lane. Problem is that the search
         // might go on far or even eternally (on a circular network), as projection simply keeps failing because the GTU is
         // actually towards the other longitudinal direction. Hence, the heuristic used before this method is called should
         // change and first always search against the direction of travel, and only consider lanes in currentLanes, while the
         // consecutive search in the direction of travel should then always find a point. We could build in a counter to prevent
         // a hanging software.
         if (nextLanes.size() == 0)
         {
             return Double.NaN; // point must be in the other direction
         }
         Throw.when(nextLanes.size() > 1, IllegalStateException.class,
                 "A position (%s) of GTU %s is not on any of the current registered lanes.", point, this.getId());
         Lane nextLane = nextLanes.iterator().next();
         otherLanesToConsider.remove(lane);
         double f = nextLane.getCenterLine().projectFractional(null, null, point.x, point.y, FractionalFallback.NaN);
         if (Double.isNaN(f))
         {
             return getDistanceAtOtherLane(nextLane, when, upstream, distance + nextLane.getLength().si, point,
                     otherLanesToConsider);
         }
         return distance + (upstream == this.currentLanes.get(nextLane).isPlus() ? 1.0 - f : f) * nextLane.getLength().si;
     }
 
     /** Time of reference position cache. */
     private double referencePositionTime = Double.NaN;
 
     /** Cached reference position. */
     private DirectedLanePosition cachedReferencePosition = null;
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public DirectedLanePosition getReferencePosition() throws GTUException
     {
         if (this.referencePositionTime == getSimulator().getSimulatorTime().si)
         {
             return this.cachedReferencePosition;
         }
         boolean anyOnLink = false;
         Lane refLane = null;
         double closest = Double.POSITIVE_INFINITY;
         double minEps = Double.POSITIVE_INFINITY;
         for (Lane lane : this.currentLanes.keySet())
         {
             double fraction = fractionalPosition(lane, getReference());
             if (fraction >= 0.0 && fraction <= 1.0)
             {
                 anyOnLink = true;
                 // TODO widest lane in case we are registered on more than one lane with the reference point?
                 // TODO lane that leads to our location or not if we are registered on parallel lanes?
                 if (refLane == null)
                 {
                     refLane = lane;
                 }
                 else
                 {
                     DirectedPoint loc = getLocation();
                     double f = lane.getCenterLine().projectFractional(null, null, loc.x, loc.y, FractionalFallback.ENDPOINT);
                     double distance = loc.distance(lane.getCenterLine().getLocationFractionExtended(f));
                     if (refLane != null && Double.isInfinite(closest))
                     {
                         f = refLane.getCenterLine().projectFractional(null, null, loc.x, loc.y, FractionalFallback.ENDPOINT);
                         closest = loc.distance(refLane.getCenterLine().getLocationFractionExtended(f));
                     }
                     if (distance < closest)
                     {
                         refLane = lane;
                         closest = distance;
                     }
                 }
             }
             else if (!anyOnLink && Double.isInfinite(closest) && getOperationalPlan() instanceof LaneBasedOperationalPlan
                     && ((LaneBasedOperationalPlan) getOperationalPlan()).isDeviative())
             {
                 double eps = (fraction > 1.0 ? lane.getCenterLine().getLast() : lane.getCenterLine().getFirst())
                         .distanceSI(new OTSPoint3D(getLocation()));
                 if (eps < minEps)
                 {
                     minEps = eps;
                     refLane = lane;
                 }
             }
         }
         if (refLane != null)
         {
             this.cachedReferencePosition =
                     new DirectedLanePosition(refLane, position(refLane, getReference()), this.getDirection(refLane));
             this.referencePositionTime = getSimulator().getSimulatorTime().si;
             return this.cachedReferencePosition;
         }
         // for (Lane lane : this.currentLanes.keySet())
         // {
         // Length relativePosition = position(lane, RelativePosition.REFERENCE_POSITION);
         // System.err
         // .println(String.format("Lane %s of Link %s: absolute position %s, relative position %5.1f%%", lane.getId(),
         // lane.getParentLink().getId(), relativePosition, relativePosition.si * 100 / lane.getLength().si));
         // }
         throw new GTUException("The reference point of GTU " + this + " is not on any of the lanes on which it is registered");
     }
 
     /**
      * Schedule the triggers for this GTU that are going to happen until the next evaluation time. Also schedule the
      * registration and deregistration of lanes when the vehicle enters or leaves them, at the exact right time. <br>
      * Note: when the GTU makes a lane change, the vehicle will be registered for both lanes during the entire maneuver.
      * @throws NetworkException on network inconsistency
      * @throws SimRuntimeException should never happen
      * @throws GTUException when a branch is reached where the GTU does not know where to go next
      */
     @SuppressWarnings("checkstyle:designforextension")
     protected void scheduleEnterLeaveTriggers() throws NetworkException, SimRuntimeException, GTUException
     {
         LaneBasedOperationalPlan plan = null;
         double moveSI;
         if (getOperationalPlan() instanceof LaneBasedOperationalPlan)
         {
             plan = (LaneBasedOperationalPlan) getOperationalPlan();
             moveSI = plan.getTotalLengthAlongLane(this).si;
         }
         else
         {
             moveSI = getOperationalPlan().getTotalLength().si;
         }
 
         // Figure out which lanes this GTU will enter with its FRONT, and schedule the lane enter events
         Map<Lane, GTUDirectionality> lanesCopy = new LinkedHashMap<>(this.currentLanes);
         Iterator<Lane> it = lanesCopy.keySet().iterator();
         Lane enteredLane = null;
         while (it.hasNext() || enteredLane != null) // use a copy because this.currentLanes can change
         {
             // next lane from 'lanesCopy', or asses the lane we just entered as it may be very short and also passed fully
             Lane lane;
             GTUDirectionality laneDir;
             if (enteredLane == null)
             {
                 lane = it.next();
                 laneDir = lanesCopy.get(lane);
             }
             else
             {
                 lane = enteredLane;
                 laneDir = this.currentLanes.get(lane);
             }
             double sign = laneDir.isPlus() ? 1.0 : -1.0;
             enteredLane = null;
 
             // skip if already on next lane
             if (!Collections.disjoint(this.currentLanes.keySet(), lane.downstreamLanes(laneDir, getGTUType()).keySet()))
             {
                 continue;
             }
 
             // schedule triggers on this lane
             double referenceStartSI = this.fractionalLinkPositions.get(lane.getParentLink()) * lane.getLength().getSI();
             // referenceStartSI is position of reference of GTU on current lane
             if (laneDir.isPlus())
             {
                 lane.scheduleSensorTriggers(this, referenceStartSI, moveSI);
             }
             else
             {
                 lane.scheduleSensorTriggers(this, referenceStartSI - moveSI, moveSI);
             }
 
             double nextFrontPosSI = referenceStartSI + sign * (moveSI + getFront().getDx().si);
             Lane nextLane = null;
             GTUDirectionality nextDirection = null;
             Length refPosAtLastTimestep = null;
             DirectedPoint end = null;
             if (laneDir.isPlus() ? nextFrontPosSI > lane.getLength().si : nextFrontPosSI < 0.0)
             {
                 LaneDirection next = new LaneDirection(lane, laneDir).getNextLaneDirection(this);
                 if (null == next)
                 {
                     // A sink should delete the GTU before we it reaches the end of the lane
                     return;
                 }
                 nextLane = next.getLane();
                 nextDirection = next.getDirection();
                 double endPos = laneDir.isPlus() ? lane.getLength().si - getFront().getDx().si : getFront().getDx().si;
                 Lane endLane = lane;
                 GTUDirectionality endLaneDir = laneDir;
                 while (endLaneDir.isPlus() ? endPos < 0.0 : endPos > endLane.getLength().si)
                 {
                     // GTU front is more than lane length, so end location can not be extracted from the lane, let's move then
                     Map<Lane, GTUDirectionality> map = endLane.upstreamLanes(endLaneDir, getGTUType());
                     map.keySet().retainAll(this.currentLanes.keySet());
                     double remain = endLaneDir.isPlus() ? -endPos : endPos - endLane.getLength().si;
                     endLane = map.keySet().iterator().next();
                     endLaneDir = map.get(endLane);
                     endPos = endLaneDir.isPlus() ? endLane.getLength().si - remain : remain;
                 }
                 end = endLane.getCenterLine().getLocationExtendedSI(endPos);
                 if (laneDir.isPlus())
                 {
                     refPosAtLastTimestep = nextDirection.isPlus() ? Length.createSI(referenceStartSI - lane.getLength().si)
                             : Length.createSI(nextLane.getLength().si - referenceStartSI + lane.getLength().si);
                 }
                 else
                 {
                     refPosAtLastTimestep = nextDirection.isPlus() ? Length.createSI(-referenceStartSI)
                             : Length.createSI(nextLane.getLength().si + referenceStartSI);
                 }
             }
 
             if (end != null)
             {
                 Time enterTime = getOperationalPlan().timeAtPoint(end, false);
                 if (enterTime != null)
                 {
                     addLaneToGtu(nextLane, refPosAtLastTimestep, nextDirection);
                     enteredLane = nextLane;
                     Length coveredDistance;
                     if (plan == null || !plan.isDeviative())
                     {
                         try
                         {
                             coveredDistance = getOperationalPlan().getTraveledDistance(enterTime);
                         }
                         catch (OperationalPlanException exception)
                         {
                             throw new RuntimeException("Enter time of lane beyond plan.", exception);
                         }
                     }
                     else
                     {
                         coveredDistance = plan.getDistanceAlongLane(this, end);
                     }
                     SimEventInterface<SimTimeDoubleUnit> event = getSimulator().scheduleEventAbs(enterTime, this, this,
                             "addGtuToLane", new Object[] {nextLane, refPosAtLastTimestep.plus(coveredDistance)});
                     addEnterTrigger(nextLane, event);
                 }
             }
         }
 
         // Figure out which lanes this GTU will exit with its BACK, and schedule the lane exit events
         for (Lane lane : this.currentLanes.keySet())
         {
             double referenceStartSI = this.fractionalLinkPositions.get(lane.getParentLink()) * lane.getLength().getSI();
             Time exitTime = null;
 
             GTUDirectionality laneDir = getDirection(lane);
             double sign = laneDir.isPlus() ? 1.0 : -1.0;
 
             double nextRearPosSI = referenceStartSI + sign * (getRear().getDx().si + moveSI);
             if (plan == null || !plan.isDeviative())
             {
                 if (laneDir.isPlus() ? nextRearPosSI > lane.getLength().si : nextRearPosSI < 0.0)
                 {
                     exitTime = getOperationalPlan().timeAtDistance(
                             Length.createSI((laneDir.isPlus() ? lane.getLength().si - referenceStartSI : referenceStartSI)
                                     - getRear().getDx().si));
                 }
             }
             else
             {
                 DirectedPoint end = null;
                 if (laneDir.isPlus() ? nextRearPosSI > lane.getLength().si : nextRearPosSI < 0.0)
                 {
                     double endPos = laneDir.isPlus() ? lane.getLength().si - getRear().getDx().si : getRear().getDx().si;
                     Lane endLane = lane;
                     GTUDirectionality endLaneDir = laneDir;
                     while (endLaneDir.isPlus() ? endPos > endLane.getLength().si : endPos < 0.0)
                     {
                         Map<Lane, GTUDirectionality> map = endLane.downstreamLanes(endLaneDir, getGTUType());
                         map.keySet().retainAll(this.currentLanes.keySet());
                         double remain = endLaneDir.isPlus() ? endPos - endLane.getLength().si : -endPos;
                         endLane = map.keySet().iterator().next();
                         endLaneDir = map.get(endLane);
                         endPos = endLaneDir.isPlus() ? remain : endLane.getLength().si - remain;
                     }
                     end = endLane.getCenterLine().getLocationExtendedSI(endPos);
                 }
                 if (end != null)
                 {
                     exitTime = getOperationalPlan().timeAtPoint(end, false);
                 }
             }
 
             if (exitTime != null && !Double.isNaN(exitTime.si))
             {
                 SimEvent<SimTimeDoubleUnit> event = new SimEvent<>(new SimTimeDoubleUnit(exitTime), this, this, "leaveLane",
                         new Object[] {lane, new Boolean(false)});
                 getSimulator().scheduleEvent(event);
                 addTrigger(lane, event);
             }
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public final Map<Lane, Double> fractionalPositions(final RelativePosition relativePosition) throws GTUException
     {
         return fractionalPositions(relativePosition, getSimulator().getSimulatorTime());
     }
 
     /** {@inheritDoc} */
     @Override
     public final Map<Lane, Double> fractionalPositions(final RelativePosition relativePosition, final Time when)
             throws GTUException
     {
         Map<Lane, Double> positions = new LinkedHashMap<>();
         for (Lane lane : this.currentLanes.keySet())
         {
             positions.put(lane, fractionalPosition(lane, relativePosition, when));
         }
         return positions;
     }
 
     /** {@inheritDoc} */
     @Override
     public final double fractionalPosition(final Lane lane, final RelativePosition relativePosition, final Time when)
             throws GTUException
     {
         return position(lane, relativePosition, when).getSI() / lane.getLength().getSI();
     }
 
     /** {@inheritDoc} */
     @Override
     public final double fractionalPosition(final Lane lane, final RelativePosition relativePosition) throws GTUException
     {
         return position(lane, relativePosition).getSI() / lane.getLength().getSI();
     }
 
     /** {@inheritDoc} */
     @Override
     public final void addTrigger(final Lane lane, final SimEventInterface<SimTimeDoubleUnit> event)
     {
         List<SimEventInterface<SimTimeDoubleUnit>> list = this.pendingLeaveTriggers.get(lane);
         if (null == list)
         {
             list = new ArrayList<>();
         }
         list.add(event);
         this.pendingLeaveTriggers.put(lane, list);
     }
 
     /**
      * Add enter trigger.
      * @param lane Lane; lane
      * @param event SimEventInterface&lt;SimTimeDoubleUnit&gt;; event
      */
     private void addEnterTrigger(final Lane lane, final SimEventInterface<SimTimeDoubleUnit> event)
     {
         List<SimEventInterface<SimTimeDoubleUnit>> list = this.pendingEnterTriggers.get(lane);
         if (null == list)
         {
             list = new ArrayList<>();
         }
         list.add(event);
         this.pendingEnterTriggers.put(lane, list);
     }
 
     /**
      * Sets a vehicle model.
      * @param vehicleModel VehicleModel; vehicle model
      */
     public void setVehicleModel(final VehicleModel vehicleModel)
     {
         this.vehicleModel = vehicleModel;
     }
 
     /** {@inheritDoc} */
     @Override
     public VehicleModel getVehicleModel()
     {
         return this.vehicleModel;
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public void destroy()
     {
         DirectedLanePosition dlp = null;
         try
         {
             dlp = getReferencePosition();
         }
         catch (GTUException e)
         {
             // ignore. not important at destroy
         }
         DirectedPoint location = this.getOperationalPlan() == null ? new DirectedPoint(0.0, 0.0, 0.0) : getLocation();
 
         synchronized (this.lock)
         {
             Set<Lane> laneSet = new LinkedHashSet<>(this.currentLanes.keySet()); // Operate on a copy of the key
                                                                                  // set
             for (Lane lane : laneSet)
             {
                 try
                 {
                     leaveLane(lane, true);
                 }
                 catch (GTUException e)
                 {
                     // ignore. not important at destroy
                 }
             }
         }
 
         if (dlp != null && dlp.getLane() != null)
         {
             Lane referenceLane = dlp.getLane();
             fireTimedEvent(LaneBasedGTU.LANEBASED_DESTROY_EVENT,
                     new Object[] {getId(), location, getOdometer(), referenceLane, dlp.getPosition(), dlp.getGtuDirection()},
                     getSimulator().getSimulatorTime());
         }
         else
         {
             fireTimedEvent(LaneBasedGTU.LANEBASED_DESTROY_EVENT,
                     new Object[] {getId(), location, getOdometer(), null, Length.ZERO, null},
                     getSimulator().getSimulatorTime());
         }
         if (this.finalizeLaneChangeEvent != null)
         {
             getSimulator().cancelEvent(this.finalizeLaneChangeEvent);
         }
 
         super.destroy();
     }
 
     /** {@inheritDoc} */
     @Override
     public final Bounds getBounds()
     {
         double dx = 0.5 * getLength().doubleValue();
         double dy = 0.5 * getWidth().doubleValue();
         return new BoundingBox(new Point3d(-dx, -dy, 0.0), new Point3d(dx, dy, 0.0));
     }
 
     /** {@inheritDoc} */
     @Override
     public final LaneBasedStrategicalPlanner getStrategicalPlanner()
     {
         return (LaneBasedStrategicalPlanner) super.getStrategicalPlanner();
     }
 
     /** {@inheritDoc} */
     @Override
     public final LaneBasedStrategicalPlanner getStrategicalPlanner(final Time time)
     {
         return (LaneBasedStrategicalPlanner) super.getStrategicalPlanner(time);
     }
 
     /** {@inheritDoc} */
     @Override
     public RoadNetwork getNetwork()
     {
         return (RoadNetwork) super.getPerceivableContext();
     }
 
     /** {@inheritDoc} */
     @Override
     public Speed getDesiredSpeed()
     {
         Time simTime = getSimulator().getSimulatorTime();
         if (this.desiredSpeedTime == null || this.desiredSpeedTime.si < simTime.si)
         {
             InfrastructurePerception infra =
                     getTacticalPlanner().getPerception().getPerceptionCategoryOrNull(InfrastructurePerception.class);
             SpeedLimitInfo speedInfo;
             if (infra == null)
             {
                 speedInfo = new SpeedLimitInfo();
                 speedInfo.addSpeedInfo(SpeedLimitTypes.MAX_VEHICLE_SPEED, getMaximumSpeed());
             }
             else
             {
                 // Throw.whenNull(infra, "InfrastructurePerception is required to determine the desired speed.");
                 speedInfo = infra.getSpeedLimitProspect(RelativeLane.CURRENT).getSpeedLimitInfo(Length.ZERO);
             }
             this.cachedDesiredSpeed =
                     Try.assign(() -> getTacticalPlanner().getCarFollowingModel().desiredSpeed(getParameters(), speedInfo),
                             "Parameter exception while obtaining the desired speed.");
             this.desiredSpeedTime = simTime;
         }
         return this.cachedDesiredSpeed;
     }
 
     /** {@inheritDoc} */
     @Override
     public Acceleration getCarFollowingAcceleration()
     {
         Time simTime = getSimulator().getSimulatorTime();
         if (this.carFollowingAccelerationTime == null || this.carFollowingAccelerationTime.si < simTime.si)
         {
             LanePerception perception = getTacticalPlanner().getPerception();
             // speed
             EgoPerception<?, ?> ego = perception.getPerceptionCategoryOrNull(EgoPerception.class);
             Throw.whenNull(ego, "EgoPerception is required to determine the speed.");
             Speed speed = ego.getSpeed();
             // speed limit info
             InfrastructurePerception infra = perception.getPerceptionCategoryOrNull(InfrastructurePerception.class);
             Throw.whenNull(infra, "InfrastructurePerception is required to determine the desired speed.");
             SpeedLimitInfo speedInfo = infra.getSpeedLimitProspect(RelativeLane.CURRENT).getSpeedLimitInfo(Length.ZERO);
             // leaders
             NeighborsPerception neighbors = perception.getPerceptionCategoryOrNull(NeighborsPerception.class);
             Throw.whenNull(neighbors, "NeighborsPerception is required to determine the car-following acceleration.");
             PerceptionCollectable<HeadwayGTU, LaneBasedGTU> leaders = neighbors.getLeaders(RelativeLane.CURRENT);
             // check collision
             if (!leaders.isEmpty())
             {
                 leaders.collect(this.collisionDetector);
             }
             // obtain
             this.cachedCarFollowingAcceleration =
                     Try.assign(() -> getTacticalPlanner().getCarFollowingModel().followingAcceleration(getParameters(), speed,
                             speedInfo, leaders), "Parameter exception while obtaining the desired speed.");
             this.carFollowingAccelerationTime = simTime;
         }
         return this.cachedCarFollowingAcceleration;
     }
 
     /** {@inheritDoc} */
     @Override
     public final TurnIndicatorStatus getTurnIndicatorStatus()
     {
         return this.turnIndicatorStatus.get();
     }
 
     /** {@inheritDoc} */
     @Override
     public final TurnIndicatorStatus getTurnIndicatorStatus(final Time time)
     {
         return this.turnIndicatorStatus.get(time);
     }
 
     /** {@inheritDoc} */
     @Override
     public final void setTurnIndicatorStatus(final TurnIndicatorStatus turnIndicatorStatus)
     {
         this.turnIndicatorStatus.set(turnIndicatorStatus);
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public String toString()
     {
         return String.format("GTU " + getId());
     }
 
 }